do planes have to keep tilting down for long flights to make up for the earth’s curvature?

Question

this is a common argument made by flat-earhters, I want to be able to refute it

In: Physics

Answer 1

The simple answer is yes. If you maintained the same angle with respect to space you would be pitching up relative to earth and that would initially cause a gain in altitude which is not desirable in the long term.

The proper answer is that it happens so slowly you can’t feel it.

At a typical airliner speed of 450 knots (nautical miles per hour) you would be doing 7.5 nautical miles per minute (450/60).

If you fly at that speed you will cover the equivalent of 1 degree of latitude (60 nautical miles) every 8 minutes (60/7.5).

So at 450 knots you would have to pitch down 1/8th of a degree every minute.

Blowing this up to a bigger scale, it’s 10,800 miles from pole to pole and that would mean 180 degrees of pitch change, @450kts that would take 24 hours (10800/450) or 1440 minutes. 180 degrees / 1440 minutes = 0.125 degrees per minute or 1/8th of a degree.